1. Field of the Invention
The present invention relates to a playback device, a playback method and a playback system.
2. Description of the Related Art
Devices that can play back various sounds (hereinafter also referred to as “playback devices”) such as, for example, a mobile music player, a voice recorder, a personal digital assistant (PDA), a laptop personal computer and a mobile telephone, are widely used. These playback devices have various functions that are used when playing back sound such as music. A noise cancellation function is known as one of these functions. The noise cancellation function is a function that, when playing back music or video in a place where ambient noise is loud, generates sound having a reverse phase to that of the ambient noise to remove or reduce the ambient noise.
The noise cancellation function has been provided in a headphone and the like as disclosed in, for example, Japanese Patent Application Publication No. JP-A-3-96199, Japanese Patent Application Publication No. JP-A-3-214892, and Japanese Patent Application Publication No. JP-A-2-231899. However, a noise cancellation headphone has a separate power source, a circuit or mechanism for cancelling noise. As a result, the structure of the noise cancellation headphone becomes large. To address this, a technology that incorporates the noise cancellation function in a playback device has been developed recently. The noise cancellation function can be used when enjoying music etc. played back by the playback device, and is well received by users.